In general, closed circuit televisions (CCTVs) installed in the indoors or the outdoors of departments, banks, exhibition centers, and factories as well as typical houses have been variously used in order to perform antitheft functions and determine the operating state of machine, the process flow, or the overall situation.
The CCTVs have been installed in a specific place to monitor all situations, which are happened in the place, at a remote plate. To this end, the CCTVs include image transmitters and display units to receive signals transmitted from the image transmitters and supply the signals to display apparatuses.
Since a monitoring function of the CCTV is lowered at night having no light or at a dark place where a user cannot confirm an object because there is no light or only weak light, a lighting unit is separately installed at the CCTV. For example, an infrared camera can be installed in the CCTV.
The infrared camera has an advantage that it may perform an optimal monitoring function even at a dark place.
FIG. 1 is a block diagram illustrating an infrared camera according to the related art.
Referring to FIG. 1, the infrared camera includes a camera module 10, a lighting module 20, a camera driving module 30, a lighting driving module 40, and a control module 50.
The camera module 10 photographs a subject and includes a lens unit 12 and a charge coupled device (CCD) sensor 14.
The lens unit 12 photographs the subject, and at least one lens may be mounted in the lens unit 12. For example, a plurality of lenses is mounted in the lens unit 12 so that the lens unit 12 may perform zoom-in/zoom-out operation.
The CCD sensor 14 detects the image of the subject passing through the lens unit 12. The detected image may be transmitted to a user at a remote place.
The CCD sensor 14 accumulates the quantity of light input through the lens unit 12, and outputs the image taken by the lens unit 12 according to the accumulated quantity of the light in response to a vertical synchronization signal.
The lighting module 20 emits light to the subject.
The lighting module 20 includes an infrared irradiating unit 22. The infrared irradiating unit 22 may be implemented as a single irradiating unit or a plurality of infrared irradiating units.
The camera driving module 30 drives the camera module 10. In detail, the camera driving module 30 drives the lens unit 12. For example, the camera driving module 30 may change a location of a lens constituting the lens unit 12 according to a zoom ratio.
The lighting driving module 40 drives the infrared irradiating unit 22.
The control module 50 controls the camera module 10 and the lighting module 20.
The control module 50 controls a location of the lens unit 12 of the camera module 10 so that the lens unit 12 may perform a zoom operation.
The control module 50 controls an operation of the lighting module 20.
The control module 50 may include a photo sensor which detects light according to an operation of a photoelectric cell serving as a device in which resistance is changed when light is irradiated to the device. The control module 50 control brightness and a flicker frequency of the lighting module 20 according to an output voltage corresponding to an amount of light input through the photo sensor.
In the foregoing infrared camera, the lighting module 20 is driven by a continuous lighting scheme, and thus emits light to the subject.
FIG. 2 is a timing chart illustrating an operation of the lighting module 20 according to the related art.
As shown in FIG. 2, the lighting module 20 continuously emits light to the subject in a continuous lighting scheme regardless of an operation of the camera module 10.
However, according to the above continuous lighting scheme, the light is generated even if the sensor does not acquire an image, so that heat is continuously generated and power consumption is increased.